Monthly Archives: December 2016

I am learning R, so this is my first attempt to create histograms in R. The data that I have is a vector of one category for each data point. For this example we will use a vector of a random sample of letters. The important thing is that we want a histogram of the frequencies of texts, not numbers. And the texts are longer than just one letter. So let’s start with this:

labels

I use the function count from the package plyr to get a matrix distribution with the different categories in column one (called "x") and the number of times this label occurs in column two (called "freq"). As I would like the histogram to display the categories from the most frequent to the least frequent one, I then sort this matrix by frequency with the function order. The function gives back a vector of indices in the correct order, so I need to plug this into the original matrix as row numbers.

Now let's do the histogram:

mp

There are many more settings to adapt, e.g., you can use cex to increase the font size for the numerical y-axis values (cex.axis), the categorical x-axis names (cex.names), and axis labels (cex.lab).

In my plot there is one problem. My categorie names are much longer than the values on the y-axis and so the axis labels are positioned incorrectly. This is the point to give up and do the plot in Excel (ahem, LaTeX!) - or take input from fellow bloggers. They explain the issues way better than me, so I will just post my final solution. I took the x-axis label out of the plot and inserted it separately with mtext. I then wanted a line for the x-axis as well and in the end I took out the x-axis names from the plot again and put them into a separate axis at the bottom (side=1) with zero-length ticks (tcl=0) intersecting the y-axis at pos=-0.3.

This is specific to my plot, Xcoord1 is one of my symbolic x-coordinates in the plot. Other than that, the code is completely independent from the used coordinates and the number of them, which makes it more flexible than my old stuff.

Usage (this will let seagreen bars at the given coordinates appear on slide 2):

In one slide of a presentation I wanted to have a background picture and overlay it with several text blocks one after the other to have the effect of the text “coming out of” the background. It is tricky to align things in LaTeX beamer, especially if you want to have them on top of each other, so this is my solution: Two minipages that cover the whole slide on top of each other.

A slide is more or less 7cm high (depending a bit on your template). There probably is a length defined for that, but I was too lazy to look for it so I took the actual value. The width of the slide is of course \textwidth. I use vertically centered alignment for the minipage, but that is up to you (see the post Set height of a minipage for the options you can give to minipage).

The way it now works is the following. Create one minipage of full width and height. Use this to display the background image. Then jump back the full height and create a second minipage of full width and height to display the text inside of that. This is the code for my slide: